| 摘要 |
PURPOSE:To make the response speed high and to improve the precision, by providing two sample hold circuits which sample and hold the output of a phase comparing circuit and driving them selectively, and synthesizing respective outputs to obtain the control voltage of a VCO. CONSTITUTION:A burst gate circuit 11 receives the signal supplied to a composite video signal input terminal 9 and the gate pulse supplied to a burst gate pulse input terminal 10 and separates the color burst from the composite video signal. A phase comparing circut 12 compared the phase of the reproduced subcarrier signal from a voltage control oscillator (VCO) 17 and that of the output signal of the burst gate circuit 11 with each other. The output of the phase comparing circuit 12 is supplied to sampling hold circuit 13 and 14. Sampling hold circuits 13 and 14 are driven at every two horizontal periods in accordance with the phase of the input burst by sampling pulses. Outputs of sampling hold circuits 13 and 14 are reduced to the control signal of the VCO17 through an adding circuit 15 and a filter circuit 16. A reproduced subcarrier signal is transmitted from the VCO17. |
